Pen arm for recording instrument



Oct. 13, 1964 H. G. LEUPOLD PEN ARM FOR RECORDING INSTRUMENT OriginalFiled April 4, 1960 INVENTOR.

United States Patent 6 Claims. (Cl. 346-439) This invention relates toindicating and recording instruments in which a pen arm, including astylus, traces a line on a record sheet and, in particular, to animproved pen arm for such instruments and constitutes a division of mypending application for Indicating and Recording Control, Serial No.19,714, filed April 4, 1960, in which the pen arm is fully disclosed.

The objects of the invention are to provide a pen arm which is of simpleconstruction; which has a high degree of flexibility in a planeperpendicular to the record sheet, and is therefore sensitive toadjustment of its bearing pressure on the record sheet; which is rigidin a plane parallel to the recording sheet and hence accuratejwhich mayreadily be lifted away from the surface of the record sheet to permitreplacing the stylus without disturbing its initial adjustment; which isof negligible weight and hence uneffected by inertia; and which isadjustable for a zero position.

As herein illustrated, the arm is pivotally supported for swingingmovement across a record sheet about an axis perpendicular to itssurface and comprises a long narrow blade of thin flexible sheet metalhaving, near its proximal end, a slot of inverted U-shape which definesa flexible central part at that end. The aforesaid part containsopenings therein for attaching elements, by means of which the blade ispivotally supported for rotation about an axis perpendicular to thechart and flexible about an axis parallel to the chart. The edges of theblade, parallel'to the legs of the U-shaped slot, are bent at rightangles to the plane of the blades to constitute stiffening flanges atthe proximal end. The distal end of the blade, forwardly of the centralpart, is fiat, tapers to a blunt point, is flexible perpendicular to theplane of the record sheet, and has at its end a stylus perpendicular tothe plane of its surface. A U-shaped frame supports the proximal end ofthe pen arm, comprising parallel arms having aligned openings forreception of a supporting shaft, one of the parallel arms havingapertures for the reception of attaching elements whereby the centralpart of the blade is secured to the frame. The blade contains an arcuateslot through which one of the attaching elements on the frame arm passand by means of which the blade may be adjusted relative to the framearm to establish its zero position. A limb is fixed at one end to one ofthe other pair of frame arms and at its opposite end by a link to theproximal end of the instrument indicator for swinging of the frame andhence of the pen arm on the record sheet in consonance with the movementof the indicator.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

- FIG. 1 is a frontelevation of the instrument embodying the pen armwhich forms the subject matter of this invention;

FIG. 2 is a right-hand side elevation of the chassis of the instrumentshowing the support for the pen arm;

FIG. 3 is a fragmentary side elevation on the left-hand side'of theinstrument showing the means for pivotally r 3,152,859 Patented Oct. 13,1964 Referring to the drawings (FIG. 1), the instrument is of the typewherein an indicator 16 is supported for movement in response to changesof pressure or temperature parallel to a scale plate 12 on which isinscribed a scale 14. The indicator 10 is fixed for movement to a shaft14 which projects forwardly from the front wall of the instrument casing0 so that the indicator arm is spaced from and parallel thereto, and thewall of the casing contains a suitable recess within which there issupported a recording sheet R of the kind commonly employed intemperature records which may be removed and replaced after each use. I

p The movement of the indicator arm 19 is traced on the recording sheetR by a pen arm 18 which is supported, as

' 10 by a link connecting the two.

The pen arm 18 is a substantially flat, long, narrow blade of flexiblemetal having a rear or proximal portion 18a, which is substantiallyrectangular and a forward or distal portion 131) which tapers from itsjunction with the rear portion, forwardly, to a relatively narrow bluntpoint to which a stylus is fixed. The rectangular rear portion 18acontains an inverted U-shaped slot, the legs of which are parallel tothe side edges of the blade, which separates therefrom a central portion180, this latter portion providing the means by which the pen arm issupported and permits tilting of the arm about an axis parallel to theplane of the blade, passing through the extremities of the legs of theU-shaped slot. The parallel edges of the blades are bent back at rightangles to the plane of the blade to provide spaced parallel stiffeningflanges 18d-13a'. The tapering forward portion of the blade is freelyflexible perpendicular to its plane surface and hence to the recordchart. j

The support for the pen arm 18 (FIG. 2) comprises a forwardly directedpost 2% secured at its rear end to the upper part of a plate 22 forminga part of the chassis of the instrument. This post has an axial bore 23which receives the rear end portion of a fixed horizontal shaft 24 (FIG.3), the latter being secured to the post 20 by a set screw 26. AU-shaped frame 28, comprising substantially parallel frame arms 30 and32,. is mounted to swing on the shaft 24. The forward arm 32 of thisframe is provided with screw-threaded openings, one above and one belowthe axis of the shaft 24, which receives screws 34 passing looselythrough holes in the central part 18c. As

thus mounted, the pen arm is rotatable about the forwardly projectingaxis of the shaft 24, parallel to the surface of the record chart and,by applying rearward pressure to the proximal end of the pen arm, thatis, beyond the end of the U-shaped slot, the arm may be rocked about anaxis passing through the lower ends of the U- shaped slot on an axisparallel to the plane of the blade thus raising the stylus at the distalend of the pen arm from its operative position in contact with therecordchart the base orproximalend of the indicator arm It so that,

as the indicator arm swings, the pen arm 18 swings likewise.

.As thus constructed, the pen arm may be comprised of sheet metaLsuch asaluminum, so as to beof light- Weight; is fiexibleperpendicular to theplane of its flat a surface; is rigid at right angles to the plane ofits surface by reason of the flanges so that it is accurate in movement;is adjustable relative to its support to enable setting it at a zeroposition; and may be easily lifted away from the recording chart withoutdisturbing its adjustment or accuracy to permit replacing the recordingchart when desired and/or to provide access to the stylus to keep thelatter clean.

The pen arm herein illustrated, as previously mentioned, is'disclosed inmy pending application Serial No. 19,714, and reference may be hadthereto for more specific details of the instrument itself if desired.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A pen arm for a recording instrument provided with a recording chartcomprising a long, flat, narrow blade adapted to be supported forpivotal movement about an axis perpendicular to its plane surfaceparallel to the recording chart, said blade having a rigid,substantially rectangular rear .part having spaced parallel,right-angularly disposed flanges at its edges and a forepart taperingfrom its junction with the rear part to a blunt point, said rear partincluding a central part flexible along a line transverseto the bladeand parallel to the plane of the blade, said flexible central partcontaining means for mounting the blade on a support .for pivotalmovement of the arm parallel to the plane of the record chart, and saidflexible central part supporting the arm for tilting about said axis tolift the forepart away from the chart and said forepart being freelyflexible throughout its length.

2. In a recording instrument of the class described, wherein a pivotallysupported pen arm swings across a recording chart, said pen arm being ofthin flexible sheet metal and having a slot of inverted U-shape in itsupper portion which defines a central panel, said panel having openingstherein for attaching elements, the margins of the pen arm adjacent tosaid slot being bent thereby to constitute stiffening flanges, and aU-shaped frame for supporting the pen arm, said frame comprisingparallel arms having aligned openings for the reception of a supportingshaft, one of said arms having apertures for the reception of attachingelements whereby the panel portion of the pen arm is secured to theframe, and means for swinging the frame thereby to move the pen armacross the recording chart.

3. A recording instrument according to claim 2 wherein the pen arm hasan arcuate slot located approximately midway its length, and aneccentric screwpassing through said slot and into a threaded hole in theapertured arm of the frame whereby the pen arm may be adjusted angullarly relatively to the center of the shaft on which the frame ismounted.

4. A pen arm comprising a relatively stiff, long, narrow blade having abutt end and a stylus-supporting end, a cantilever support intermediatethe ends of the blade, said cantilever support being joined to the bladeintermediate the ends and extending from its place of junction with theblade away from the stylus-supporting end toward the butt end, and meansat the distal end of the cantilever support for securing it to a stafffor rotation of the arm about an axis perpendicular thereto, saidcantilever support at its junction with the blade affording a flexiblehinge on which the blade is bendable by pressure applied to the butt endabout an axis transverse 'to the blade to effect movement of the stylusend in an opposite direction.

5. A pen arm comprising a long, narrow blade having a relatively stiffpart, a relatively flexible part extending from one end of the stiffpart, a stylus fixed to the distal end of the flexible part, and acantilever support joined at its proximal end to the still part adjacentthe junction of the stiff part with the flexible part, said cantileversupport extending away from said junction toward the distal end of thestiff part, and means at the distal end of the cantilever support forsecuring it to a staff for rotation of the arm about an axisperpendicular thereto, said cantilever support at its junction with theblade affording a flexible hinge on which the blade is bendable bypressure applied to the butt end about an axis transverse thereto toeffect movement of the stylus in the opposite direction.

6. A pen arm comprising a long, narrow blade having a relatively stiffpart, a relatively flexible part of narrower width extending from oneend of the stiff part, a stylus fixed to the distal end of the flexiblepart, acantilever situated in the stiff ,part with its proximal endintegral with the stiff part adjacent the junction of the stiff partwith the flexible ,part, said cantilever lying within the plane surfacesofthe stiff part, means at the distal end of the cantilever for securingit to a staff for rotation of the arm about an axis perpendicularthereto, said cantilever at its junction with the blade affording aflexible hinge onwhich the blade is bendable by pressure applied to thedistal end of the stiff part about an axis transverse to the blade toeffect movement of the stylus end in the opposite direction.

References Cited in the file of thispatent UNITED STATES PATENTS1,136,648 Bristol Apr. 20, 1915 2,173,061 Erbguth Sept. 12, 1 9392,500,657 Bowditch Mar. 14, 1950

4. A PEN ARM COMPRISING A RELATIVELY STIFF, LONG, NARROW BLADE HAVING A BUTT END AND A STYLUS-SUPPORTING END, A CANTILEVER SUPPORT INTERMEDIATE THE ENDS OF THE BLADE, SAID CANTILEVER SUPPORT BEING JOINED TO THE BLADE INTERMEDIATE THE ENDS AND EXTENDING FROM ITS PLACE OF JUNCTION WITH THE BLADE AWAY FROM THE STYLUS-SUPPORTING END TOWARD THE BUTT END, AND MEANS AT THE DISTAL END OF THE CANTILEVER SUPPORT FOR SECURING IT TO A STAFF FOR ROTATION OF THE ARM ABOUT AN AXIS PERPENDICULAR THERETO, SAID CANTILEVER SUPPORT AT ITS JUNCTION WITH THE BLADE AFFORDING A FLEXIBLE HINGE ON WHICH THE BLADE IS BENDABLE BY PRESSURE APPLIED TO THE BUTT END ABOUT AN AXIS TRANSVERSE TO THE BLADE TO EFFECT MOVEMENT OF THE STYLUS END IN AN OPPOSITE DIRECTION. 